Abstract

Non-standard database applications require adequate modeling facilities for their application objects which in general have an internal structure to be maintained by the database system. For this purpose, the database system has to provide fast access to such an object as a whole as well as to its components. In systems which support complex objects with a statically established structure, clustering of the objects' components along this structure is a widespread means to enhance efficiency. Systems which support the dynamic definition of complex objects' structures, however, cannot predict the characteristics of accesses to the database, and therefore have more problems in finding a storage structure that is useful for at least the majority of the accesses. In this paper, we propose a cluster mechanism that supports the flexibility and dynamism of the molecule-atom data model at the efficiency of static structure clustering. We discuss different alternatives for its design, taking into account the query processing strategies of the underlying database system. We address some problems concerning optimization that emerge from the dynamic structure definition and show some possible solutions.